Coordinate measuring instrument

ABSTRACT

A coordinate measuring instrument, wherein a measuring element support member (1) having a measuring element (2) is movably supported on a mount plate (3), this measuring element (2) is abutted against the surface and the like of a work to be measured, which is mounted on the mount plate (3), and relative movement values between this measuring element (2) and the work are detected to measure a configuration and the like of the work. In this measuring instrument, vertical surfaces (3A, 3B, 50A and 50B) are formed on the mount plate (30) and air bearings (47, 52 and 53) opposed to these vertical surfaces are provided on legs (8 and 9) of the measuring element support member (1), so that the measuring element support member (1) can be regulated in its position in a direction of X-axis.

TECHNICAL FIELD

This invention relates to coordinate measuring instrument including atwo-dimensional and a tridimensional measuring instruments for measuringa configuration and the like of a work to be measured by movements of ameasuring element relative to a mount plate mounted thereon with thework, and more particularly to a coordinate measuring instrument, inwhich relative movement guide of a measuring element support member tothe mount plate is improved.

BACKGROUND ART

There has heretofore been known a coordinate measuring instrument,wherein a measuring instrument is moved relative to a work to bemeasured, which is mounted on a mount plate, and a configuration and thelike of the work are measured from relative displacement values of thismeasuring element. The coordinate measuring instruments of the typedescribed are widely used in various fields of industries for displayingthe advantages in raising the measuring accuracy, improving theoperating efficiency of measurement and the like.

FIG. 1 shows a conventional coordinate measuring instrument. Thiscoordinate measuring instrument is a tridimensional measuring instrumentof the type, wherein a mount plate is fixed and the measuring element ismovable. A gate-shaped measuring element support member 103 constitutinga moving mechanism is mounted on a mount plate 102 rested on a base 100.This measuring element support member 103 comprises: a right and a leftsupports 104 and 105; a transverse member 106 transversely racked acrosstop portions of these supports 104 and 105 in a direction of X-axis; aslider 107 provided in a manner to be movable along the transversemember 106; and a spindle 108 provided in a manner to be movable in adirection perpendicular to the slider 107, i.e. a direction of Z-axis. Ameasuring element 109 is secured to the bottom end of this spindle 108.

Movement of the measuring element 109 in a direction of Y-axis isperformed due to the movement of the measuring element support member103 along a guide rail member 110 affixed to the top surface of themount plate 102, movement of the measuring element 109 in the directionof X-axis is performed due to the movement of the slider 107 along thetransverse member 106, and further, movement of the measuring element109 in the direction of Z-axis is performed due to the movement of thespindle 108 in the vertical direction. The guide rail member 110 issecured thereto with a detector 111 for the direction of Y-axis. Adisplacement value in the direction of Y-axis of the measuring element109 due to the movement of the measuring element support member 103along the guide rail member 110 is detected by this detector 111, adisplacement value in the direction of X-axis of the measuring element109 due to the movement of the slider 107 is detected by a detector 112secured to the transverse member 106, and further, a displacement valuein the direction of Z-axis of the measuring element 109 due to thevertical movement of the spindle 108 is detected by a detector 113secured to the slider 107. The work to be measured is rested on andaffixed to the top surface of the mount plate 102, whereby the measuringelement 109 is brought into contact with the surface of the work andmoved tridimensionally, so that the configuration and the like of thework can be measured.

In the conventional technique shown in FIG. 1, since the guide railmember 110 as being the reference of guide in the direction of Y-axis issecured to the top surface of the mount plate 102, troublesomeassembling and adjusting works for securing the mounting accuracy of theguide rail member 110 are required, and the effective area of the topsurface of the mount plate 102 is restricted by the guide rail, member110, whereby the size of the work to be rested on the mount plate 102 isrestricted. There have been such disadvantages that, since the guiderail member 110 becomes an obstacle to the work, when the work iscarried onto the mount plate, only after the direction of the work ischanged, the work can be mounted on the top surface of the mount plate102, and that the height of the measuring element support member 103 isincreased due to the height of the guide rail member 110, so that theheight of the tridimensional measuring instrument is increasedgenerally.

In addition to the above, it is difficult to operate the tridimensionalmeasuring instrument from the side where the guide rail member 110 isprovided, whereby the operating position is restricted. When thedetector 111 is secured to the guide rail member 110 as shown in FIG. 1,there is a possibility that this detector 111 is contaminated or damagedduring the operation of mounting the work onto the mount plate 102, thuspresenting the disadvantage about the safety of the detector 111. Thegate-shaped measuring element support member 103 is merely rested on themount plate 102, whereby, when an external force acts sideways on themeasuring element support member 103, there has a possibility that theelement measuring support member 103 turns over.

According to the above-described conventional technique, when a left leg103A and a right leg 103B of the measuring element support member 103are provided with air bearings, respectively, so as to move themeasuring element support member 103 relative to the mount plate 102, ifthe slider 107 is moved along the transverse member 106 and thismovement is stopped at a position close to either the left support 104or the right support 105, then the measuring element support member 103is inclined and rotated about an axis parallel to the direction ofY-axis due to the fluctuations in the position of the center of gravityof the measuring element support member 103, whereby the measuringelement 109 is varied in posture and an error occurs in a measuredresult of the work. When it is tried to obviate the disadvantagesdescribed above by the raise of air pressure, the measuring elementsupport member 103 is increased in its floating value from the mountingplate 102, whereby the measuring element support member 103 becomesunstable, thus unabling to obviate the disadvantages.

The present invention has been developed to obviate the above-describeddisadvantages of the prior art, and is based on that, since the topsurface of the mount plate is finished to be smooth and horizontal forresting thereon the work in particular, it is relatively easy that othersurfaces are finished with high accuracy, securing the perpendicularitythereof with the top surface.

The present invention has as its object the provision of a coordinatemeasuring instrument, wherein, the mount plate itself is formed toprovide the guide reference surface for the movement of the measuringelement support member, whereby the provision of the guide rail memberon the mount plate is dispensed with, so that the workabilities inassembling, adjustment and the like are improved, the effective area ofthe top surface of the mount plate is enlarged, the operation ofmounting the work is facilitated and the controllability and the like ofthe measuring instrument are bettered. Moreover, the legs of the movingmechanism holding the measuring element as the measuring element supportmember are provided with air bearings opposed to vertical surfacesformed on the mount plate, whereby resistance against an external forcein the traverse direction is generated in the measuring element supportmember, so that a possibility that the measuring element support memberturns over can be eliminated.

SUMMARY OF THE INVENTION

To achieve the above-described object, the present inventioncontemplates that, in a coordinate measuring instrument, wherein a workto be measured, which is mounted on the mount plate, and a measuringelement held by a moving mechanism are moved relative to each other atleast in two directions of axes perpendicularly intersecting each otherout of the directions of X-, Y- and Z-axes, and a configuration and thelike of the work are measured from relative displacement values, themount plate is formed of a stone material being rectangular in verticalsection and the top surface thereof is made horizontal, this mount plateis provided over a base, with a space formed therebetween, and positionregulating means in the direction of X-axis, which are formed on themount plate and opposed to two vertical surfaces parallel to each otherand extending in the direction of Y-axis are provided on both legs ofthe moving mechanism, respectively, so that these legs are made movablerelative to the mount plate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing a conventional example of thecoordinate measuring instrument;

FIG. 2 is a front view showing a first embodiment of the coordinatemeasuring instrument according to the present invention;

FIG. 3 is a side view of FIG. 2;

FIG. 4 is an enlarged, partially sectional view of FIG. 3;

FIG. 5 is a partially sectional front view of FIG. 4;

FIG. 6 is a partially enlarged, sectional view of FIG. 2;

FIG. 7 is a sectional side view of FIG. 6;

FIG. 8 is a front view showing the coordinate measuring instrumentaccording to a second embodiment of the present invention;

FIG. 9 is a side view thereof;

FIG. 10 is a partially enlarged, sectional view of FIG. 8;

FIG. 11 is a partially enlarged, sectional view of FIG. 9;

FIG. 12 is a partially enlarged view of FIG. 10; and

FIG. 13 is a view in the direction indicated by the arrows from lineXII--XII in FIG. 12.

BEST MODE FOR WORKING THE INVENTION

FIG. 2 is the front view showing the coordinate measuring instrumentaccording to the first embodiment and FIG. 3 is the side view thereof.This coordinate measuring instrument is a tridimensional measuringinstrument. A measuring element support member 1 constitutes a mechanismfor moving a measuring element 2 in directions of X-, Y- and Z-axes, anddisposed therein with a mount plate 3. As shown in FIG. 2, the mountplate 3 is provided at opposite sides in the longitudinal directionthereof with support members 4, respectively. The mount plate 3 ismounted through these support members 4 on a base 5, with a space beingformed therebetween.

As shown in FIG. 2, the measuring element support member 1 comprises: aleft and a right supports 6 and 7; legs 8 and 9, which are integrallyconnected to the bottoms of the supports 6 and 7; a transverse member 10racked across the tops of the supports 6 and 7 in the direction ofX-axis and a connecting member 11 inserted through the space formedbetween the mount plate 3 and the base 5, for connecting the legs 8 and9 to each other. In consequence, the measuring element support member 1having a front shape being of a generally square frame, surrounding themount plate 3. In this embodiment, the transverse member 10 is formed ofa stone material and slidably mounted thereon with a slider 12. Aspindle 14 is received in a case 13 integrally formed on the slider 12in a manner to be movable in the direction of Z-axis, i.e. the verticaldirection, and the measuring element 2 is secured to the bottom end ofthis spindle 14.

The legs 8 and 9 move relative to the mount plate 3, whereby themeasuring element 2 is moved in the direction of Y-axis. The slider 12moves along the transverse member 10, whereby the measuring element 2 ismoved in the direction of X-axis. The spindle 14 moves in the verticaldirection, whereby the measuring element 2 is moved in the direction ofZ-axis.

A raised member 15 extending in the longitudinal direction of the mountplate 3 is provided on a right side surface 3A of the mount plate 3 inFIG. 2, and a main scale 16 is secured to this raised member 15 as shownin FIG. 3. The main scale 16 and a scale body 17 secured to the leg 9constitute an optical detector as shown in FIG. 4. The scale body 17incorporates therein an index scale opposed to the main scale 16, alight emitting element, a light receiving element and the like. When theleg 9 moves right and left in FIG. 3, a light emitted from the lightemitting element is turned into an optical wave form by the main scale16 and the index scale and received by the light receiving element. Theoptical wave form thus received is converted into an electric signal,whereby a movement value of the leg 9 in the direction of Y-axis, i.e. adisplacement value of the measuring element 2 in the direction of Y-axiscan be measured.

As shown in FIG. 6, a raised member 18 is secured to the transversemember 10. A main scale 19 secured to this raised member 18 and a scalebody 20 provided on the slider 12 constitute a detector in the directionof X-axis having a construction similar to the above, whereby adisplacement value in the direction of X-axis of the measuring element 2due to the movement of the slider 12 along the transverse member 10 ismeasured by this detector. As shown in FIG. 7, a main scale 21 issecured to a side surface of the spindle 14. A block 22 is received andfixed into the case 13 integrally formed on the slider 12. A scale body23 is provided in the block 22. The main scale 21 and the scale body 23constitute a detector in the direction of Z-axis having a constructionsimilar to the above. A displacement value in the direction of Z-axis ofthe measuring element 2 is detected by this detector due to the verticalmovement of the spindle 14.

The spindle 14 is connected thereto with one end of a wire 26 running byguided by rollers 24 and 25, a balance weight 27 is connected to theother end of the wire 26, and the weight of the spindle 14 is supportedby the balance weight 27. Two groups of rollers 28 and 29 are providedabove and below the block 22, whereby the spindle 14 is moved in thevertical direction through the rotary guide action of the groups ofrollers 28 and 29.

To obviate the measuring errors, the scale body 17 shown in FIG. 4 isadjustable in its posture of inclination to the main scale 16. Thisadjustment will now be described in detail. The leg 9 is affixed theretowith a bracket 30, to which the scale body 17 is tightened and affixedthrough a locking bolt, not shown. Two screws 31 and 32 are threadedinto the bracket 30. These screws 31 and 32 are brought into abuttingcontact with stepped portions of two side portions 17A and 17B of thescale body 17. When the locking bolt is loosened and the screws 31 and32 are linearly moved through rotating operation, the scale body 17 isrotated about an axial line passing through a direction perpendicularlyintersecting a paper surface of FIG. 4, so that an angle of posture ofthe scale body 17 relative to the main scale 16 can be adjusted. Each ofthe adjusting mechanisms similar to the above is provided with each ofthe scale bodies 20 and 23 for detecting in the directions of X-axis andY-axis as shown in FIGS. 6 and 7.

Movements of the measuring element 2 in the respective directions of X-,Y- and Z-axes are performed through operations of pushing the measuringelement support member 1 and the like. As shown in FIG. 4, the leg 9 isprovided with a mechanism 33 for finely moving the leg 9 in thedirection of Y-axis. As shown in FIGS. 4 and 5, this finely movingmechanism 33 comprises: a fine movement knob 34 rotatably secured to apredetermined position of the leg 9; a generally U-shaped clamper member35 capable of rocking about a screw rod 34A of the fine movement knob34; and a clamp knob 36 whose screw rod 36A is threaded into one end ofthis clamper member 35. The clamp knob 36 is rotated to clamp the raisedmember 15 between the bottom end of the screw rod 36A and the other endof the clamper member 35, whereby the clamper member 35 is integratedwith the mount plate 3. When the fine movement knob 34 is rotated inthis state, feeding action occurs between the screw rod 34A and theclamper member 35, into which this screw rod 34A is threaded, with theresult that the leg 9, and in its turn, the measuring element supportmember 1 is finely moved relative to the mount plate 3 in the directionof Y-axis.

As shown in FIGS. 6 and 7, each of the finely moving mechanisms 39 and42 in the direction of X-axis and Z-axis, which comprise the finemovement knobs 37 and 40, the clamp knobs 38 and 41 and the like similarto the above, are provided on the slider 12 and the case 13,respectively.

The side surfaces 3A, 3B to the left and right and the top surface 3C ofthe mount plate 3 as being the stone surface plate as shown in FIG. 5are finished with high accuracy, and the respective plane accuraciesthereof are secured, the top surface 3C is made horizontal and the sidesurfaces 3A, 3B are formed into vertical surfaces constituting guidereference surfaces in the direction of Y-axis, and the rectangularnessof the side surfaces 3A, 3B to the top surface 3C is secured highly. Inthis embodiment, the top surface 3C of the mount plate 3 is formed witha threaded hole 43 to be utilized for fixing the work to be measured,which is mounted on the top surface 3C. Furthermore, as shown in FIG. 2,a connecting bar 44 is racked across the left and right supports 6 and 7to connect the supports 6 and 7 to each other, whereby the measuringelement support member 1 is improved in its strength, so that an errorin measuring due to deformation of the measuring element support member1 can be prevented from occurring.

As shown in FIG. 5, each of the left and right legs 8 and 9 is formedinto an inverted L-shape in looking from the front, and these legs 8 and9 have top portions 8A and 9A and side portions 8B and 9B, which areopposed to the top surface 3C and the side portions 3A and 3B of themount plate 3, respectively.

Top air bearings 45 are provided in the top portions 8A and 9A of thelegs 8 and 9, respectively. These top air bearings 45 are opposed to thetop surface 3C of the mount plate 3, while being pressed by forward endsemispherical portions of cap screws 46, respectively. Side air bearing47 constituting means for regulating the positions in the direction ofX-axis of the measuring element support member 1 are provided in theside portions 8B and 9B of the legs 8 and 9, respectively. These sideair bearings 47 are also opposed to the side surfaces 3A and 3B of themount plate 3, which being pressed by forward end semispherical portionsof cap screws 48, respectively. Respective two pairs of the top airbearings 45 and the side air bearings 47 are disposed on both sides ofthe legs 8 and 9 in the longitudinal direction of the mount plate 3.

Air blows out from the top air bearings 45 and the side air bearings 47,whereby the measuring element support member 1 is made slidable on themount plate 3, so that the measuring element support member 1 can movein the direction of Y-axis. At this time, in the tridimensionalmeasuring instrument, movement of the measuring element support member 1in the direction of Y-axis is performed by utilizing the side surfaces3A and 3B of the mount plate 3 as the guide surfaces. More specifically,the measuring element support member 1 is moved by utilizing the mountplate 3 itself as the guide member. Since the top surface 3C of themount plate 3 is precision-finished for mounting the work, it isrelatively easy that the side surfaces 3A and 3B are subjected to flatwork, with the perpendicularity of these side surfaces 3A and 3B beingmaintained at high accuracy. In consequence, such troublesome works canbe dispensed with that the guide rail members are secured to the topsurface of the mount plate, with the parallelism and the like beingsecured, and so on, as in the conventional technique shown in FIG. 1.

When the top air bearings 45 and the side air bearings 47 blow out air,the legs 8 and 9 tend to expand outwardly to the left and right in FIGS.2 and 5 due to the reaction force of air blow-out from the side airbearings 47. However, as aforesaid, the legs 8 and 9 are connected toeach other through the connecting member 11, so that this expansion canbe avoided.

As described above, in the tridimensional measuring instrument, since noguide rail is provided on the top surface 3C of the mount plate 3, thewhole surface of the top surface 3C can be used as the surface formounting thereon the work. More specifically, the effective area of thetop surface 3C of the mount plate 3 is enlarged, so that a large-sizedwork to be measured can be mounted thereon. Furthermore, when the workis mounted onto the top surface 3C of the mount plate 3, there is noobstacle such as the guide rail member and the like on the top surface3C, whereby there is no need of changing the direction of the work, sothat the work as it is can be disposed on the top surface 3C of themount plate 3, thus facilitating the carry-in and carry-out operationsof the work. Further, there is no guide rail member protruding upwardlyfrom the top surface 3C of the mount plate 3, whereby the height of themeasuring element support member 1 can be reduced accordingly, so thatthe height of the tridimensional measuring instrument can be decreased.

Since the guide rail member is not used, either the left or right sideof the mount plate 3 in FIGS. 2 and 5 is in the opened state, so thatthe tridimensional measuring instrument can be operated not only fromthe front but also both the right and left sides of the mount plate 3,thus improving the controllability. In this embodiment, the main scale16 constituting the detector in the direction of Y-axis is provided onthe side surface 3A of the mount plate 3, whereby, when the work iscarried in or out-of the top surface 3C of the mount plate 3,possibilities that this main scale 16 is contaminated or damaged arereduced, so that the detector can be held in safety.

In addition to the above, in the tridimensional measuring instrument,the top air bearings 45 and the side air bearings 47, which are opposedto the top surface 3C and the side surfaces 3A and 3B of the mount plate3, respectively, are provided in the legs 8 and 9 of the measuringelement support member 1, and the legs 8 and 9 have the construction ofembracing the mount plate 3 from the top and the sides thereof, so that,even if an external force in the lateral direction acts on the measuringelement support member 1, this external force can be effectivelysupported by the side portions 8B and 9B of the legs 8 and 9, therebypreventing the measuring element support member 1 from turning over.

Description will hereunder be given of the second embodiment. In thisembodiment, same reference numerals are used to designate same orsimilar parts corresponding to ones as shown in the first embodiment, sothat the description will be omitted or simplified.

This second embodiment features that, differing from the embodiment,wherein the vertical surfaces each constituting the guide referencesurface in the direction of Y-axis are provided on the side surfaces ofthe mount plate 3, vertical surface 50A and 50B are formed on a bottomrail 50 provided on the undersurface of the mount plate 3, air bearings52 and 53, which are opposed to extended surface of 50A and 50B of thesevertical surfaces, are provided on the connecting member 54, andfurther, position regulating means in the direction of Z-axis isprovided.

Referring to FIGS. 8 through 13 showing the second embodiment, thebottom rail 50 is secured to the central portion in the direction ofX-axis on the undersurface of the mount plate 3, this bottom rail 50extends in the longitudinal direction of the mount plate 3, i.e. thedirection of Y-axis, and has a length equal to the mount plate 3. Inthis embodiment, the bottom rail 50 is made of a stone materialsimilarly to the mount plate 3, consequently, may be formed separatelyof the mount plate 3 as shown, or formed integrally with the mount plate3. As shown in FIG. 10, a raised member 56 provided thereon with a mainscale 55 is secured to the undersurface of the bottom rail 50, and boththe main scale 55 and the raised member 56 extend in the direction ofY-axis.

The main scale 55 and a scale body 58 secured to the connecting member54 constitute the optical detector in the direction of Y-axis. An indexscale opposed to the main scale 55, the light emitting element, thelight receiving element and the like are received in the scale body 58,whereby a displacement value of the measuring element 2 in the directionof Y-axis is detected similarly to the preceding embodiment. There isprovided stopper means, not shown, for regulating the limit in movementof the measuring element support member 1 in the direction of Y-axis.

For example, this stopper means is formed by securing raised memberseach being made of an elastic material such as rubber to the left andright side surfaces of the connecting member 54 shown in FIG. 11. Themeasuring element support member 1 is moved in the direction of Y-axis,whereby this raised member abuts against one of the support members 4,so that the measuring element support member 1 can be limited in itsmovement in the direction of Y-axis.

In the second embodiment also, the posture of the scale body 58 relativeto the main scale 55 can be adjusted through an adjusting mechanism.This posture adjusting mechanism is shown in FIGS. 12 and 13. A bracket60 is connected to the connecting member 54 through two bolts 61, andthis bracket 60 is provided at the bottom portion thereof with two armportions 60A and 60B spaced apart from each other in the direction ofY-axis as shown in FIG. 13. Mounting members 62 are connected toopposite side surfaces of the scale body 58 in the direction of Y-axis,and these mounting members 62 are tightened and fixed to the armportions 60A and 60B through screws 63. Adjusting screws 64 arethreadably coupled into the bracket 60 at positions opposed to themounting members 62. When the screws 63 are loosened and the adjustingscrews 64 are rotated to move linearly, the scale body 58 is rotatedabout the vertical axial line in FIG. 12 only for a value commensurateto a clearance formed between the arm portions 60A, 60B and the screws63, so that the scale body 58 is adjusted in its posture relative to themain scale 55.

Top planar portions 3D are formed on both portions in the direction ofX-axis of the top surface 3C of the mount plate 3, and bottom planarportions 3E are formed on both portions in the direction of X-axis ofthe undersurface. These top planar and bottom planar portions 3D and 3Eare formed to provide highly accurate surfaces being parallel to eachother.

The top air bearings 45 opposed to the top planar surface 3D in the leftand right legs 8 and 9 are pressed by forward end semispherical portionof top bolts 65. In the connecting member 54, which constitutes a movingmechanism together with the measuring element support member 1 and thelegs 8 and 9, the bottom air bearings 66 opposed to the bottom planarportions 3E are pressed by top bolts 67. These top air bearings 45 andthe bottom air bearings 66 constitute means for regulating the positionof the measuring element support member 1 in the direction of Z-axis.

As shown in FIG. 11, the pairs of the top air bearings 45 are providedon the sides of the legs 8 and 9 in the direction of X-axis, and eachbottom air bearing 66 is provided in the central portion in thedirection of Y-axis.

The vertical surfaces 50A and 50B, which constitute the guide referencesurfaces of the bottom rail 50 in the direction of Y-axis, areaccurately perpendicular to the top surface 3C of the mount plate 3. Thebottom rail 50 may be formed integrally on the mount plate 3.

The side air bearings 52 and 53, which are opposed to the verticalsurfaces 50A and 50B, are pressed by tap bolts 70 and 71 in the centralportion of the connecting member 54. These side air bearings 52 and 53constitute means for regulating the position of the measuring elementsupport member 1 in the direction of X-axis and two pairs of the sideair bearings 52 and 53 are provided on both sides in the direction ofY-axis.

In order to provide the side air bearings 52 and 53, it becomesnecessary to provide a protruded portion between the legs 8 and 9 on theside of undersurface of the mount plate 3 (In this embodiment, theconnecting member 54). However, in FIG. 10, the support members 4 forsupporting the mount plate 3 on the base 5 are secured to the oppositesides of the mount plate 3 in the direction of Y-axis, whereby, even ifthe measuring element support member 1 moves in the direction of Y-axisrelative to the mount plate 3, the portions where the side air bearings52 and 53 are provided, are not abutted against anyone of the supportmembers 4.

In this tridimensional measuring instrument, the movement of themeasuring element support member in the direction of Y-axis isperformed, while the position in the direction of Z-axis thereof beingregulated by the top air bearings 45 and the bottom air bearings 66,which are opposed to the top planar portions 3D and the bottom planarportions 3E and in parallel to each other with high accuracy, and theposition in the direction of X-axis thereof being regulated by the sideair bearings 52 and 53, which are opposed to the vertical surfaces 50Aand 50B.

According to the second embodiment as described above, the measuringelement support member 1 is positionally invariably provided relative tothe mount plate 3 not only in the direction of X-axis but also in thedirection of Z-axis, whereby, even when the slider 12 is moved in thedirection of X-axis, the slider 12 reaches one end of the transversemember 10 and the measuring element support member 1 is greatly changedin its position of the center of gravity, the measuring element supportmember 1 can avoid being inclined and rotated, thus adding such anadvantage that a measuring error due to a shift in position of themeasuring element 2 can be prevented from occurring.

The detectors used in the measuring instrument according to thisembodiment as described above have been of the optical encoders,however, these detectors may be of optional types such as magnetic ones.Furthermore, the coordinate measuring instrument in this embodiment hasbeen the tridimensional measuring instrument, however, the presentinvention is applicable to a two-dimensional measuring instrument,wherein the measuring element moves two-dimensionally on a surfaceparallel to the top surface of the mount plate. The measuring instrumentaccording to this embodiment has been of the type, wherein the mountplate is affixed and the measuring element is moved relative to themount plate, however, the present invention is applicable to a measuringinstrument of the type, wherein the mount plate is moved relative to themeasuring element. In short, any measuring instrument may be used, onlyif the measuring instrument is of the type, wherein the work, which ismounted on the mount plate, and the measuring element are moved relativeto each other.

The position regulating means in the direction of Z-axis and in thedirection of X-axis have been constituted by the air bearings, however,these means may be constituted by rollers, for example. Morespecifically, any optional position regulating means may be used, onlyif the means are of the types, wherein the measuring element is movedrelative to the mount plate, while being regulated in position in thedirections of Z and X-axes.

The present invention as described above can provide the coordinatemeasuring instrument, wherein an effective area on the top surface ofthe mount plate is enlarged, the workability such as the mounting of thework is bettered, the controllability of the measuring instrument isimproved, the hight of the measuring instrument is reduced, further, themeasuring element is made to have the resistance against the externalforces in the lateral direction, and the possibility that the measuringelement support member turns over can be eliminated.

INDUSTRIAL AVAILABILITY

The present invention can be applied generally to the field of measuringindustry for measuring the tridimensional configuration and the like ofthe work.

We claim:
 1. A coordinate measuring instrument, wherein a work to bemeasured, which is mounted on a mount plate, and a measuring elementheld by a moving mechanism having a pair of legs are moved relative toeach other at least in two directions of axes perpendicularlyintersecting each other out of the directions of X-, Y- and Z-axes, andconfiguration and the like are measured from relative displacementvalues, characterized in that: said mount plate is provided over a basewith a space formed therebetween; and position regulating means in thedirection of X-axis, which are formed on said mount plate and opposed totwo vertical surfaces parallel to each other and extending in thedirection of Y-axis are provided on both legs of said moving mechanism,respectively, so that said legs are made movable relative to said mountplate.
 2. A coordinate measuring instrument as set forth in claim 1,wherein said mount plate is provided over said base, with the spacebeing formed therebetween through support members.
 3. A coordinatemeasuring instrument as set forth in claim 2, wherein said legs areconnected to each other through a connecting member crossing on theundersurface's side of said mount plate.
 4. A coordinate measuringinstrument as set forth in claim 1, wherein said vertical surfaces areformed on opposite sides of said mount plate.
 5. A coordinate measuringinstrument as set forth in claim 1, wherein the bottom surface of saidmount plate is formed to provide a surface parallel to the top surfacethereof and position regulating means in the direction of Z-axis areprovided in said both legs.
 6. A coordinate measuring instrument as setforth in claim 5, wherein said position regulating means in thedirection of Z-axis are formed of air bearings.
 7. A coordinatemeasuring instrument as set forth in claim 1, wherein said positionregulating means in the direction of X-axis are formed of air bearings.8. A coordinate measuring instrument as set forth in claim 1, whereinsaid vertical surfaces are formed on opposite side surfaces in thedirection of X-axis of a rail provided on the undersurface of said mountplate and extending in the direction of Y-axis.
 9. A coordinatemeasuring instrument as set forth in claim 8, wherein a detector fordetecting a position of said measuring element in the direction ofY-axis is provided on the undersurface of said rail.
 10. A coordinatemeasuring instrument as set forth in claim 9, wherein: said detector hasa main scale and a scale body including an index scale opposed to saidmain scale and a light emitting element; and said scale body isadjustable in its posture.